It is often necessary or desirable to administer, deliver or inject material into a particular target location or zone in the human body for therapeutic or diagnostic treatments or procedures. The injectable material can include a variety of different fluids, including orthopedic cements, bone and other bone augmentation materials, drugs, contrast agents, cell-based treatment materials such as stem cells, and other fluids for a variety of different diagnostic or therapeutic treatments or procedures. Although the subject matter of this disclosure is not limited to orthopedic treatments in general or spinal treatments in particular, treatment of spinal conditions, including treatment of vertebral compression fractures, is an area where injection of a material into the vertebral body is a particularly common treatment.
A vertebral compression fracture (VCF) is a common spinal condition that typically involves the injection of material as part of the treatment. A vertebral compression fracture is a crushing or collapsing injury to one or more vertebrae. Vertebral compression fractures are generally, but not exclusively, associated with osteoporosis, metastasis, and/or trauma. Osteoporosis reduces bone density, thereby weakening bones and predisposing them to fracture. The osteoporosis-weakened vertebrae can collapse during normal activity and are also more vulnerable to injury from shock or other forces acting on the spine. In severe cases of osteoporosis, actions as simple as bending forward can be enough to cause a vertebral compression fracture.
One technique used to treat vertebral compression fractures is injection of a bone augmentation material directly into the fractured vertebral body. This procedure is commonly referred to as vertebroplasty. More particularly, vertebroplasty involves injecting bone augmentation material (for example, bone cement, bone growth agent, allograph material or autograph material) into the collapsed vertebra to stabilize and strengthen the crushed vertebra. Other techniques for treating vertebral compression fractures employ the injection of bone cement into cavities formed within the cancellous bone of a vertebral body. Such cavities may be formed by removal of cancellous bone using cavity/channel creation tools or by compaction of the cancellous bone using expansion of balloons within the vertebral body. Bone cement is also injected in or around implants that are inserted into the vertebral body to separate and support the vertebral endplates.
Injection of bone augmentation material into the vertebral body, however, sometimes carries with it the risk of “extravasation.” For example, in vertebroplasty and certain other procedures, bone augmentation material, and particularly bone cement, is introduced directly into the vertebral body with the physician preferably viewing the cement dispersion via fluoroscopy during the procedure. This type of injection requires particular care as there is a risk of extravasation, which includes undesired leakage or dispersion of the bone augmentation material into undesired areas, such as into the vicinity of the spinal cord or nerves.
Accordingly, although the subject matter described herein is not limited to orthopedic or spinal treatments, it has particular benefits in the treatment of VCF, and is significant because there has been and continues to be a long felt need for devices and methods to control or limit the flow materials during injection into the body and in particular to control and/or limit the flow of bone augmentation material, such as bone cement and related fluids, injected into the vertebral body during vertebroplasty and certain other related VCF treatments.